Wireless communication networks support wireless communication between various stations adapted according to various protocols and standards including IEEE 802.11, Bluetooth, advanced mobile phone services (AMPS), Global system for mobile communications (GSM), code division multiple access (CDMA), wireless application protocols (WAP), local multi-point distribution services (LMDS), multi-channel multi-point distribution systems (MMDS), and the like.
An IEEE 802.11 compliant wireless local area network (WLAN) links a plurality of stations to one or more access points (APs) that in turn may connect the stations to the Internet. Each access point utilizes one of a plurality of available channels to create a basic service set (BSS). A set of stations join the BSS to have a wireless communication via AP. The IEEE 802.11 standard started with unlicensed 2.4 GHz spectrum band and later expanded to unlicensed 5 GHz spectrum band. The 2.4 GHz band provides 3 orthogonal 20 MHz channels whereas the 5 GHz band provides 25 orthogonal 20 MHz channels. The IEEE 802.11n working group introduced a concept called “channel bonding” which refers to the concurrent use of two adjacent 20 MHz channels or a total of 40 MHz of spectrum bandwidth for a single, “bonded” communication channel. By providing twice the bandwidth of conventional 20 MHz channels, these bonded channels effectively achieve data transmission rates that are almost double those of the original 20 MHz channels. The IEEE 802.11ac standard operates on 5 GHz band and promises to provide very high data rate of up to 7 Gbps by using up to 160 MHz bandwidth and 8 spatial streams for data transmissions.
A part of the 5 GHz band on the other hand is utilized for the operation of various radar systems. Thus, while operating at 5 GHz in the regulatory domains, 802.11ac BSS can face interference from radar signals on some of the channels under Dynamic Frequency Selection (DFS) region. These channels that may face interference from radar signals are known as Dynamic Frequency Selection channels, and the remaining channels on the 5 GHz where no radar operations are allowed are known as non-DFS channels. The interference can also happen from the other WLANs (BSSs) operating in the same channel. Thus, the access point should have the intelligence to react to the interference that degrades the channel quality and the throughput below a desired threshold by dynamically switching the operating channel to an optimal channel.
The present art describes operation and channel selection on 20 MHz and 40 MHz channels only which was the case before the introduction of IEEE 802.11ac. Moreover, the present state of art addresses the channel selection problem in different ways such as by obtaining the channel quality and then selecting the best channel for operation or by considering the receiver signal strength indicator (RSSI) of each channel to choose the best channel.
In certain arts, the channel quality is measured in terms of receiver signal strength indicator (RSSI), Clear Channel Assessment (CCA) busy periods and periodicity; and a channel is selected based on the channel quality report for BSS operation. Further, certain techniques have been described wherein the access point determines interference on its operating wireless channel and considers RSSI and packet failures to choose the best channel to operate on.
However, the existing methods and systems related to channel switching and dynamic frequency allocation after detecting radar signal in the operating channel do not choose wide band channels as they do not consider the bandwidth of potential channels during channel switch. Moreover, the existing art does not address how to perform Dynamic Frequency Selection considering different bandwidths of available channels i.e., 20/40/80/160/80+80 MHz channels in the 5 GHz band of wireless LAN.
At present none of the existing methods related to Dynamic Frequency Selection, to the best of our knowledge, exploit different bandwidths that are made available as part of IEEE 802.11ac for wideband operation in an efficient manner. Also, they do not talk about retaining the primary channels for ensuring minimal disruption to the on-going Quality of Service (QoS) transmissions such as Voice and Video sessions while switching the channel. Moreover, the maximum mean effective isotropically radiated power (E.I.R.P.) restricted by the regulatory domains is not considered during dynamic frequency selection.
In order to utilize the wideband channels that are available under IEEE 802.11ac and optimally serve the stations in case of interference due to the presence of radar signal and other unwanted signals, there remains a need for a method and system for dynamically selecting best available wideband channels by monitoring the performance of the operating channel as well as the non-operating channels in 5 GHz regulatory domains.